Did Albert Einstein marry one of his cousins?

For years, people online have shared an alleged fact: Albert Einstein married one of his cousins.

For example, on Aug. 3, 2026, a TikTok user shared a video (archived) showing three people reacting while reading a Google artificial-intelligence summary of the famous physicist’s love life.

The Google “AI Overview” displayed in the clip read in part:

Albert Einstein had several love interests throughout his life, with his first wife being Mileva Maric, a Serbian physicist and his fellow student. He later married his cousin, Elsa Einstein, after divorcing Mileva, though his affairs continued after this marriage as well.

Other users have shared the rumor about Einstein marrying his cousin on Facebook (archived), Instagram (archived), LinkedIn (archived), Reddit (archived) and X (archived). Some users commented with the same joke playing on the idea of both Einstein’s theory of relativity and the pair allegedly being relatives. For example, one Threads user posted (archived), “Einstein married his cousin Elsa. Even his marriage was relative.”

In short, historical documentation confirms this claim is true. Britannica.com published that Elsa Einstein was a first cousin on Albert Einstein’s mother’s side and a second cousin on his father’s side, making the pair double cousins. A 1929 newspaper article (pages: 1 | 2) profiling Elsa Einstein serves as one of the oldest journalistic records reporting the pair being cousins.

Biographer Antonina Vallentin’s 1954 biography of Albert Einstein provided intimate details of the couple’s relationship. An excerpt from the work appears later in this article.

Explaining the cousin connection

In 1876 in Germany, Rudolf Einstein and his wife, born Fanny Koch, welcomed their second child with the birth of Elsa Einstein.

Three years later, in 1879, Hermann Einstein and his wife, born Pauline Koch, welcomed baby Albert Einstein, also in Germany.

Historical records show Fanny and Pauline Koch were sisters, making Albert and Elsa Einstein maternal first cousins. Records also show Elsa Einstein’s paternal grandfather, Raphael Einstein, and Albert Einstein’s paternal grandfather, Abraham Einstein, were brothers, making Albert and Elsa Einstein paternal second cousins.

Elsa Einstein reportedly married textile trader Max Lowenthal in 1896, with the couple having two daughters and a son — the latter dying soon after his birth — then divorced in 1908.

Albert Einstein married Mileva Maric, a fellow physics student from Serbia, in Bern, Switzerland, in 1903, with the couple later having two sons.

In the 1980s, researchers located (archived) a trove of letters from Albert Einstein’s life in a Berkeley, California, safety deposit box, some reportedly revealing (archived) the married couple had a daughter named Lieserl born prior to their marriage in 1902. Research appeared to have found little in the way of credibly confirmed information about the child’s life.

The Associated Press (archived) reported on the fallout of Albert Einstein’s first marriage and his affair with Elsa Einstein reportedly beginning in 1912 or earlier:

Mileva had been reluctant to move to Berlin, not only because she disliked the sprawling metropolis but also because she was suspicious of Einstein’s cousin, Elsa Einstein-Lowenthal, who lived there.

Her suspicions were correct. Einstein had been having an affair with Elsa since at least 1912.

In 1913, Einstein wrote to Elsa: “I treat my wife as an employee whom I cannot fire.”

He described Mileva as “an unfriendly, humorless creature who does not get anything out of life and who, by her mere presence, extinguishes other people’s joy of living.”

In 1916, when Einstein asked for a divorce, Mileva suffered a physical and mental breakdown. The divorce was final in 1919, and Einstein married Elsa shortly afterward.

A German-language marriage record appeared to confirm Albert Einstein wedded Elsa Einstein in Berlin in June 1919. The first page appeared to display the name Elsa Lowenthal next to the “2.” space, while the second page showed a signature for Elsa Einstein, suggesting she possibly hadn’t yet changed her last name back to Einstein after her first marriage ended in divorce.

In 1921, Albert Einstein received the Nobel Prize for physics, not for his theory of relativity as sometimes rumored, but instead for what the awarding organization described as “his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect.”

Elsa Einstein died (archived) in December 1936 from a heart ailment. Albert Einstein died in April 1955 of an aortic aneurysm. No records document the double-cousin couple as having biological children together.

Vallentin’s biography of Einstein

Vallentin’s biography of Einstein, “The Drama of Albert Einstein,” further documented Albert and Elsa Einstein’s relationship, saying their marriage “seemed the most obvious thing in the world to both of them”:

The meeting between Einstein and his cousin Elsa was the beginning of the only permanent personal relationship in his life: thenceforward their relationship dominated his private life. He had known her as a child, when she used to visit his younger sister, but having as a boy no interest in little girls, he had completely forgotten her existence. Now he met a woman who was already mature, who had been divorced after an unhappy marriage, and who was the doting mother of two wistful and frail little girls. She must have been very charming; people who met her later in life disregarded the total lack of coquetry in her manner to admire her regular features and remarkably fair complexion. Her lively expression saved her from being merely pretty. She had bright blue, extremely myopic eyes, and a humorous mouth. 

Einstein, distrustful of all intrusions into his private life, must have been on the defensive against every stranger, but with Elsa it was as if he rediscovered something with which he had been familiar all his life and his defenses disappeared. They had many memories in common, both their own and their elders’; they recalled old times, in a language spiced with dialect, inherited proverbs and sayings; they put forward mysterious interpretations of events long past: tiny incidents that were both tragic and grotesque. They would exchange understanding glances, like those of old friends, and smiles that were much older than their relationship as man and wife. They met on a common ground of friendship and self-confidence which remained with them always. 

The Internet Archive hosts a digital copy of the biography, free to borrow for users who sign up for an account. The author references Elsa Einstein on pages 15, 66-69 and others.

For further reading, we previously investigated several alleged Einstein quotes about insanity, the rich controlling means of communication, people who observe evildoers and World War IV.

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